Table 2

Comparison of breast cancer risk factors between study participants and nonrespondents to the mammogram and/or food frequency components of the Minnesota Breast Cancer Family Study

Study samplea (n = 1679)Nonrespondentsb (n = 3540)Pc
Mean ± SD
Age (yr)61.4 ± 11.462.2 ± 13.20.06
Anthropometric variables
Body mass index (kg/m2)27.1 ± 5.826.6 ± 5.50.002
WHR0.85 ± 0.080.85 ± 0.110.457
Weight156.1 ± 33.7154 ± 32.90.095
Hormone-related variables
Age at first birth23.0 ± 4.222.0 ± 5.30.63
Age at last birth31.1 ± 5.531.1 ± 7.10.78
Number of live births3.1 ± 1.963.1 ± 4.040.07
Age at menarche13.2 ± 5.513.5 ± 6.80.09
%
Menopausal status
Premenopausal17.519.50.07
Postmenopausal82.580.5
Oral contraceptive use
Never51.557.30.001
Former47.842.0
Current0.70.7
Hormone replacement use
Never53.565.40.001
Former17.415.3
Current29.119.3
Mammographic density (%)
0–2025.319.6d0.001
21–4051.861.3
41–6016.415.4
61–805.83.3
81–1000.70.4
Relationship to breast cancer proband
Sister1.81.30.001
Daughter6.95.6
Granddaughter18.616.9
Niece32.527.2
Marry-in40.249.0
Lifestyle variables
Alcohol consumption
Never14.615.90.51
Monthly62.462.0
Weekly18.318.0
Daily4.74.1
Smoking history
Never58.052.40.001
Former, ≤20 pack-years18.316.4
Former, >20 pack-years11.610.6
Current, ≤20 pack-years2.65.0
Current, >20 pack-years9.515.6
Exercise
Low33.238.90.001
Moderate41.237.8
High25.623.3
  • a Total n for study sample includes those women who were included in the study sample (n = 1508) and the additional 92 that were excluded from analyses because of incomplete food frequency questionnaires and 79 women excluded because of breast cancer.

  • b Includes those who responded to the mammogram component only, the food frequency component only, or neither component.

  • c P for χ2 test or t test.

  • d Mammographic density was computed at the time of the study for those “nonrespondents” who returned a mammogram.